Exposures of human populations to environmental chemicals can be reduced by engineering interventions. Superfund sites have occurred because systems were developed for materials processing, energy and product production and waste management without consideration of human and environmental health information. Combustion systems are used both for treatment and destruction of various types of waste materials, and for the production of energy and materials. In these applications, they have the potential to produce air pollution and hazardous by products, which may result in exposures to human populations and damage tot he environment. Fundamental information is necessary for improved design and control of combustion processes to reduce toxic emissions. In the proposed research, through a combination of experiments and theoretical modeling, we seek understanding of the processes and mechanisms that result in byproduct synthesis in high temperature environments. Identifying conditions under which toxic combustion byproducts are formed and establishing the chemical kinetic mechanisms that identify major pathways of formation are important for developing methods for intervention and control. In addition, we will continue to develop simple, reliable, direct, real-time combustion species monitoring techniques to ensure reliable system control. Toxic compounds to be studied will include species under study in the biomedical part of the program, including chlorinated hydrocarbons and metals. Specifically, the aims for the project are; 1. Expand our studies of the chemistry and interactions of chlorinated hydrocarbons to more complex, heavily chlorinated hydrocarbons, and hydrocarbon/chlorinated hydrocarbon mixtures in post-flame environments. 2. Continue development of non-intrusive monitoring techniques (such as in situ FTIR and ELFFS) for application to metals and other hazardous species produced in flames or in the post-flame environment. 3. Study the behavior of metals and metal species in flames and in the post-flame environment, with the goal of identifying conditions that produce specific metal compounds in the emissions either in the gas phase or in small particles. 4. Assess and develop intervention and control strategies, such as post- flame fuel injection and secondary particle injection to reduce toxic byproduct emissions or enhance byproduct recovery for recycling and reuse. The long-range goal of this program project is to improve the high processes themselves and to provide a means of on-line real time monitoring of air emissions, that efforts contribute to the reduction of exposures to toxic combustion byproducts.